System with guides and tools of different flexibility

ABSTRACT

A system includes a flexible guide tube, an actuator coupled to the flexible guide tube and configured to move at least a portion of the flexible guide tube, a processor, and memory storing computer-executable instructions. When executed by the processor, the computer-executable instructions cause the system to: identify at least one factor associated with insertion or removal of a tool configured to be inserted through or removed from the flexible guide tube; identify, in a first configuration of the flexible guide tube and based on the at least one factor, one or more sections of the flexible guide tube having one or more bends that the tool cannot traverse; and command the actuator to automatically move the flexible guide tube to a second configuration without manual steering by a user, wherein the second configuration does not include the one or more bends that the tool cannot traverse.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of International Patent ApplicationNo. PCT/US2015/048254 filed Sep. 3, 2015; which claims priority fromU.S. Provisional Application 62/048,210 filed Sep. 9, 2014, which areincorporated by reference herein in their entireties.

BACKGROUND

Many types of minimally invasive medical procedures involve inserting aguide tube to a target site and then inserting and removing one or moretools through the guide tube. In some procedures, the guide tube may beflexible enough to follow a natural lumen, but the tool or a portion ofthe tool may not be as flexible as the guide tube. As a result,insertion or removal of the tool may be difficult. For example, a biopsyneedle at the distal end of a lung biopsy instrument may be stiffer thanthe lung catheter used to guide the lung biopsy instrument. During alung biopsy, a lung catheter following branching airways may bend to anextreme angle in order to reach a targeted nodule, and the biopsy needlemay be difficult to push or insert through the sharp bend in thecatheter. In particular, when a biopsy needle is being inserted througha catheter, a physician may apply an insertion force intended to slidethe needle along a tool lumen in the catheter, and the walls of the toollumen may apply a force that deflects or even bends the biopsy needle asthe needle is being inserted. However, the interaction of the needlewith the walls of the tool lumen causes friction and may cause theneedle to dig into the catheter, making insertion of the tool difficult.Also, an insertion force that is too large may damage the biopsy needleor the catheter. Similarly, when removing a tool from a convoluted guidetube, the stiff part of the tool may be difficult to pull through sharpbends without applying potentially damaging force. Systems and methodsfor efficient insertion and removal of tools from flexible guide tubesare thus desired.

SUMMARY

In accordance with an aspect of the invention, a robotically controlledmedical system can determine and record the shape of a guide tube in atarget configuration. If the shape of the flexible guide tube in thetarget configuration includes one or more bend with a radius ofcurvature that is sharper than the predetermined minimum radius ofcurvature or if the target configuration is otherwise unsuitable forinsertion/removal of a tool, a control system for the tool can inform auser to activate or can automatically activate a tool insertion/removalmode. In the tool insertion/removal mode, the control system identifiesa configuration of the guide tube suitable for insertion or removal ofthe tool. This insertion/removal configuration may, for example, be aconfiguration in which the distal end of the guide tube is pulled backto a location that is along the target configuration and associated withthe most proximal bend having a radius of curvature less than a minimumpermitted radius. The control system when in the tool insertion/removalmode can automatically retract distal tip of the guide tubesubstantially along the recorded shape until the guide tube is in theinsertion/removal configuration. The tool can then be inserted orremoved without requiring excessive or damaging force. The controlsystem can then automatically return the guide tube, e.g., containingthe inserted tool, along the recorded shape back to the targetconfiguration. For return of the guide tube from the insertion/removalconfiguration to the target configuration, a stiffer part of the tool,e.g., the needle in a biopsy instrument, may be within the steerablesection of the guide tube, so that the steerable section may bend orflex the tool as needed to automatically retrace the recorded shape andreturn the guide tube to the target configuration. Removal of the toolcan be the reverse of the insertion process. In particular, the guidetube containing the tool may be retracted from the target configurationto the insertion/removal configuration where the tool can be removedwithout need of excessive force. A tool can thus be inserted before useand removed or replaced after use without damaging the tool or guidetube, without requiring large insertion/removal force, and withoutrequiring medical personnel to manually navigate the guide tuberepeatedly between the target configuration and an insertion/removalconfiguration.

One specific embodiment is a medical system including a guide tube witha steerable distal tip, a drive system, and control logic. The drivesystem may control pitch and yaw of the distal tip of the guide tube,control the shape of the distal portion of the guide tube, and/orcontrol movement of the guide tube along an insertion direction. Thecontrol logic operates the drive system and may include a shape analysismodule and a movement module. For example, the shape analysis module mayidentify bends in a target configuration of the guide tube that are toosharp for a tool to easily traverse, and the movement module may controlthe drive system for automatic movement of the guide tube between thetarget configuration and an insertion/removal configuration, which maycorrespond to the distal tip of the guide tube being at a locationassociated with a bend that is too sharp for the tool to traverse.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a failed attempted to deploy a biopsy needle througha lung catheter having a sharp bend.

FIG. 2 is a block diagram of one implementation of a medical systemincluding a lung catheter.

FIGS. 3A and 3B show alternative implementations of a distal tip of aflexible instrument.

FIG. 4 is a flow diagram of an example process for deploying a toolthrough a flexible guide tube.

FIG. 5A shows an empty guide tube deployed to a target configuration.

FIG. 5B illustrates the retraction of the empty guide tube from thetarget configuration of FIG. 5A to an insertion or removalconfiguration.

FIG. 5C illustrates the guide tube in an insertion or removalconfiguration of FIG. 5B after a tool has been inserted.

FIG. 5D illustrates navigation of the guide tube containing the toolbetween the insertion or removal configuration of FIG. 5C and the targetconfiguration of FIG. 5A.

FIG. 5E illustrates a tool being inserted further for use in a medicalprocedure after the guide tube was returned to the target configuration.

FIG. 6 is a flow diagram of an example process for removing a tool froma flexible guide tube.

The drawings illustrate examples for the purpose of explanation and arenot of the invention itself. Use of the same reference symbols indifferent figures indicates similar or identical items.

DETAILED DESCRIPTION

Many minimally invasive medical procedures involve inserting a guidetube to a target site and then inserting and removing one or more toolsthrough the guide tube. In some of these procedures, the guide tube isflexible enough to follow a natural lumen and position a distal tip ofthe guide tube at a target location with a target orientation. The guidetube after being steered to its target location has what is referred toherein as a target configuration, and in the target configuration, theguide tube may have a shape conforming to the shape of the natural lumenwith no or minimal distortions. Steering the guide tube to the targetconfiguration is typically a process that may require a physician's timeand attention. For example, a physician may use a control device, e.g.,a joystick, to control a steerable portion of the guide tube and mayselect a path for insertion of the guide tube based on video images fromthe perspective of the distal tip of the guide tube or from theperspective of an external imaging or sensing device. Once the guidetube is in the target configuration, the physician may try to insert atool through the guide tube until the distal tip of the tool extendsfrom the distal end of the guide tube, where the tool may be used in amedical procedure such as collecting body tissue samples. However, theshape of the guide tube in the target configuration may be such thatinsertion of the tool is difficult or impossible without inconvenienceor even risking damage to the tool, the guide tube, or a patient.

FIG. 1 illustrates a situation in which the guide tube is a lungcatheter 110 that is deployed through airways 120 to a targetconfiguration in which a distal tip of catheter 110 points at a nodule122. Catheter 110 may be a flexible guide tube having at least one toollumen for guiding of a tool such as a biopsy needle 130 or other medicalprobe. Catheter 110 may particularly be a steerable device, e.g., havingan actuated distal section 112 capable of controlling the pitch and yawof a distal tip 114 of catheter 110. Distal section 112 may, forexample, be controlled by pulling on cables or tendons (not shown) thatextend from distal section 112 along the length of catheter 110 to adrive mechanism (not shown). Catheter 110 may also be steerable using acomputerized control system that operates the drive system to controlthe pitch and yaw of tip 114, the shape of distal section 112, or thelength of catheter 110 inserted through airways 120.

A user such as a physician may deploy lung catheter 110 by firstintroducing tip 114 to the bronchial system of a patient. In oneimplementation, a biopsy instrument 130 is not in catheter 110 duringinitial deployment of catheter 110. For example, a removable camerasystem (not shown) may be inserted in the main or tool lumen of catheter110 during the initial deployment of catheter 110. Alternatively,catheter 110 may include a permanent vision system (not shown) thatleaves the main lumen available for a tool such as biopsy needle 130. Ineither case, a user such as a physician can view the bronchial systemthrough a vision system that provides the perspective of tip 114 or canuse an external sensor system to identify the location of distal tip 114relative to airways 120. The user can then manipulate a mastercontroller such as a joystick to control the pitch and yaw of distal tip114 and movement of catheter 110 along an insertion axis, and in thatway, navigate distal tip 114 to a target configuration for a biopsy of anodule 122 in airways 120. During the navigation, a computer system canmediate pitch, yaw, and insertion movement of distal tip 114, or some orall of the movement of catheter 110 may be under direct manual ortactile control. See, for example, co-filed U.S. patent application Ser.No. 15/509,154, entitled “Flexible Medical Instrument,” which is herebyincorporated by reference in its entirety. FIG. 1 illustrates catheter110 after reaching a target configuration, regardless of the techniqueused to reach the target configuration.

Biopsy needle 130 generally includes a needle section 132 that may bemade of a material such as stainless steel attached to the distal end ofa more compliant section 134 made from a material such asPolytetrafluoroethylene. In general, section 132 may be stiffer, lessflexible, or less compliant than catheter 110 or section 134, andsection 134 may be at least as flexible or compliant as catheter 110.The target configuration of catheter 110 may include many bends, and inFIG. 1, catheter 110 has a bend 116 with a radius of curvature and anangular size such that a tip or needle section 132 of a biopsy needle130 is unable to traverse bend 116 without application of an insertionforce that is unacceptably large. As a result, needle section 132 maywedge against the interior walls of the tool lumen in catheter 110. Amore flexible needle section 132 could be employed to allow needlesection 132 to more easily traverse sharp bends such as bend 116, butmaking needle section 132 more flexible or floppy may make taking abiopsy sample more difficult. In general, tools require stiffness inorder to perform their intended medical task, so that configurations ofguide tube 110 in which a tool 130 such as biopsy needle 130 cannot befully advanced to the distal tip of guide tube 110 may occur.

A physician manually inserting biopsy needle 130 through catheter 110may feel resistance to insertion of needle 130 greatly increase whenneedle 130 reaches bend 116 and may then know that needle 130 cannot befully deployed through catheter 110 while catheter 110 is in the targetconfiguration. Similarly, if a physician navigates a guide tube suchcatheter 110 containing a tool such as biopsy needle 130 to a targetconfiguration containing a sharp bend, the physician may find that asharp bend 116 halts removal of the tool. In one implementation, aphysician may encounter a situation in which a tool such as biopsyneedle 130 cannot be further advanced or retracted through a guide tubesuch as catheter 110 without unacceptable force or risk and may activatean insertion/removal control mode that performs automated movements ofthe guide tube as described further below. For example, a control systemfor catheter 110 may automatically, partially retract catheter 110 to atool insertion configuration in which needle 130 can be inserted beforecatheter 110 with the inserted tool 130 is automatically returned to thetarget configuration. Similarly, the control system for catheter 110 mayautomatically retract catheter 110 containing biopsy needle 130 to atool removal configuration where needle 130 can be removed and catheter110 can remain ready for insertion of a replacement tool. In general,the insertion configuration may be the same as or different from theremoval configuration, and the insertion/removal configuration is usedherein to refer to a configuration that an insertion configuration or aremoval configuration.

As an alternative to having a human user identify a problem withinsertion or removal of a tool, a control system for a guide tube suchas a lung catheter can measure and evaluate the shape of the guide tubein its target configuration to determine whether a tool can be insertedor removed along the target configuration of the guide tube withoutrequiring unacceptable force or unacceptable risk. If the targetconfiguration is unsuited to insertion or removal of the tool, thecontrol system can inform a physician and determine a toolinsertion/removal configuration suitable for insertion or removal of thetool. The physician can then choose to use the insertion/removal controlmode, or the control system can automatically switch to theinsertion/removal control mode without need of human intervention.

FIG. 2 schematically illustrates one specific implementation of amedical system 200 in accordance with one embodiment of the invention.In the illustrated embodiment, system 200 includes a lung catheter 210,a steering drive mechanism 220, an insertion drive mechanism 230,control logic 240, an operator interface 250, and a sensor system 260.

Catheter 210 is a generally flexible device having one or more lumensincluding a tool lumen that can accommodate interchangeable probes suchas a biopsy need or a vision system. Flexible catheters can be madeusing a braided structure such as a woven wire tube with inner or outerlayers of a flexible or low friction material such aspolytetrafluoroethylene (PTFE). In one embodiment, catheter 210 includesa bundle of lumens or tubes held together by a braided jacket and areflowed (i.e., fused by melting) jacket of a material such as PolyetherBlock Amide (Pebax). A steerable distal section 216 (e.g., a structuresuch as shown in FIG. 3A or 3B and described further below) can formpart of the distal end of catheter 210.

Catheter 210 as noted above includes at least one tool lumen forinterchangeable probe systems and may further include smaller lumens forpull wires, sensor lines, illumination fibers, or permanent visionsystems or for introduction or removal of fluids or medication to orfrom a work site. In the illustrated embodiment, catheter 210 has aproximal section 212 attached to steering drive mechanism 220 and adistal section 214 that extends from proximal section 212. In theillustrated implementation, distal section 214 includes steerablesection 216, which has a mechanical structure that may be actuatedthrough pull wires that extend from steering drive mechanism 220 throughproximal section 212 and distal section 214 and connect to steerabledistal segment 216. Alternatively or additionally, mechanical elementsanywhere along the length of catheter 210 may be similarly articulatedor actuated using drive tendons or other mechanisms.

The overall length of catheter 210 for procedures performed in lungs orairways may be about 60 to 80 cm or longer with distal section 214 beingabout 15 cm long and steerable segment 216 being about 4 to 5 cm long.Distal section 214 may have a smaller diameter than does proximalsection 212. During a medical procedure, a portion of proximal section212 and all of distal section 214 may be inserted along a natural lumensuch as an airway of a patient. A smaller diameter for distal section214 may permit use of distal section 214 in lumens that are too smallfor proximal section 212, but a larger diameter for proximal section 212may facilitate manual manipulation or inclusion in proximal section 212of more or larger structures or devices such as electromagnetic sensingcoils 262 that may not fit in distal section 214.

Steerable segment 216 is remotely controllable and particularly has apitch and a yaw that can be controlled using actuating tendons, e.g.,pull wires. Steerable segment 216 may form all or part of distal section214 and may be simply implemented as a multi-lumen tube of flexiblematerial such as Pebax with suitable connections to the actuatingtendons. Steerable segment 216 may be more flexible than the remainderof catheter 210 to assist in isolating actuation or bending to steerablesegment 216 when steering drive mechanism 220 pulls on actuatingtendons. Catheter 210 can also employ additional features or structuressuch as use of Bowden cables for actuating tendons to prevent actuationfrom bending proximal section 212 (or bending any portion of distalsection 214 other than steerable segment 216). However, the entirety ofcatheter 210 should have sufficient compliance and a sufficiently smallminimum radius of curvature to follow or conform to the shape of anatural lumen, e.g., airways.

FIG. 3A shows one specific embodiment in which steerable segment 216 ismade from a tube 310 that in catheter 210 of FIG. 2 defines the distalend of a main lumen 312 for a probe system and contains smaller lumensfor actuating tendons 330 and for a shape sensor not shown in FIG. 3A.In particular, main lumen 312, which continues back through catheter210, has an opening at the distal tip 314 of steerable segment 216, anda tool such as a biopsy needle inserted through main lumen 312 canextend past distal tip 314 to interact with tissue during a medicalprocedure. In the illustrated embodiment, four tendons 330 are placed90° apart and surrounding lumen 312 to facilitate steering instrument110 in pitch and yaw directions defined by the locations of tendons 330.A reflowed jacket, which is not shown in FIG. 3A to better illustratethe internal structure of steerable segment 316, may also cover tube310. As shown in FIG. 3A, tube 310 is cut or formed to create a seriesof flexures 320. Tendons 330 connect to distal tip 314 of steerablesegment 216 and extend back to steering drive mechanism 220. Tendons 330can be wires, cables, Bowden cables, hypotubes, or any other structuresthat are able to transfer force from steering drive mechanism 220 todistal tip 314 and capable of limiting the bending of proximal section212 when steering drive mechanism 220 pulls on tendons 330. Inoperation, pulling harder on any one of tendons 330 tends to causesteerable segment 216 to bend in the direction of that tendon 330. Toaccommodate repeated bending, tube 310 may be made of a material such asNitinol, which is a metal alloy that can be repeatedly bent with littleor no damage.

The implementation of steerable section 216 shown in FIG. 3A does notinclude a camera or other elements of a vision system that can provide auser with a view, e.g., a stereoscopic view, from the perspective ofdistal tip 314. However, a probe that includes a vision system can beinserted through main lumen 312 to provide a view to a user, forexample, during navigation of catheter 210 along a natural lumen such asan airway. A vision probe may be removed for replacement with anothertool or probe such as a biopsy needle. Alternatively, as shown in FIG.3B, a steerable section 216 may include permanent components 340 of avision system, so that a probe such as a biopsy needle may reside inmain lumen 312 while the vision components 340 are in operation. Visioncomponents 340 may include, for example, a camera system, anillumination system, or the ends of optical fibers that carryillumination or image light between the distal and proximal ends ofcatheter 210.

Steering drive mechanism 220 of FIG. 2, which pulls on tendons 330 toactuate distal steerable segment 216, includes a mechanical system ortransmission 224 that converts the movement of actuators 222, e.g.,electric motors, into movements of or tensions in tendons 330 that runthrough catheter 210 and connect to distal steerable segment 216. Themovement and pose of distal steerable segment 216 can thus be controlledthrough computerized selection or generation of respective actuationsignals for actuators 222 in steering drive mechanism 220. In additionto actuation of steerable segment 216, steering drive mechanism 220 maybe used to control other movement of catheter 210 such as rotation orroll of the proximal end of catheter 210, which may also be poweredthrough actuators 222 and transmission 224. Backend mechanisms ortransmissions that are known for flexible-shaft instruments could ingeneral be used or modified for steering drive mechanism 220. Forexample, some known drive systems for flexible instruments are describedin U.S. Pat. App. Pub. No. 2010/0331820, entitled “Compliant SurgicalDevice,” which is hereby incorporated by reference in its entirety.Steering drive mechanism 220 in addition to actuating catheter 210should allow removal and replacement of probes in catheter 210, so thatthe structure of drive mechanism 220 should be out of the way duringsuch operations.

In the illustrated implementation of FIG. 2, steering drive mechanism220 is mounted on insertion drive mechanism 230, which includesactuators 232 and a mechanical system 234 used to move steering drivemechanism 220 and catheter 210 along the insertion direction. Mechanicalsystem 234 may include a slide or a track on which steering drivemechanics 220 is movably mounted. Actuators 232 may be drive motors thatpower movement of steering drive mechanics 220 and catheter 210according to actuation signals that control logic 240 selects orgenerates.

Control logic 240 controls actuators 222 in steering drive mechanism 220to selectively pull on the tendons as needed to actuate distal steerablesegment 216 and control the pitch and yaw of the distal tip of catheter210 and controls actuators 232 to control movement in the insertiondirection of the distal tip of catheter 210. In general, control logic240 operates in response to commands from a user, e.g., a surgeon,physician, or other human user using operator interface 250, and theuser may operate interface 250 in response to a view that a visionsystem provides or measurements from sensor system 260. Control logic240 may be implemented using a general purpose computer with suitablesoftware, firmware, and/or device-specific interface hardware tointerpret signals from operator interface 250 and sensor system 260 andto generate actuation signals for actuators 222 and 232.

In the illustrated embodiment, control logic 240 includes multiplemodules 241, 242, 243, 244, and 245 that implement different processesor modes for use of catheter 210. As used herein, the term “module”refers to a combination of hardware (e.g., a processor such as anintegrated circuit or other circuitry) and software (e.g., machine- orprocessor-executable instructions, commands, or code such as firmware,programming, or object code). A combination of hardware and softwareincludes hardware only (i.e., a hardware element with no softwareelements), software hosted at hardware (e.g., software that is stored ata memory and executed or interpreted or at a processor), or hardware andsoftware hosted at hardware.

Navigation module 241 may be employed while a user steers catheter 210to a target location or configuration. Navigation module 241 may act tointerpret or convert control signals from operator interface 250 and togenerate actuation signals for actuators 222 and 232. Operator interface250 may include standard input/output hardware such as a vision system,a display, a keyboard, a joystick, a foot pedal, a pointing device suchas a mouse, or similar I/O hardware that may be customized or optimizedfor a surgical environment. In general, operator interface 250 providesinformation to the user and receives instructions from the user. Forexample, operator interface 250 may indicate the status of system 200and provide the user with data including images and measurements made insystem 200. One type of instruction that the user may provide throughoperator interface 250, e.g., using a joystick or similar mastercontroller, indicates the desired pitch, yaw, and insertion movement ofdistal steerable segment 216. Using such inputs, control logic 240 cangenerate actuation signals for actuators 222 and 232 in drive mechanisms220 and 230. Other instructions from the user may select an operatingmode of control logic 240.

Shape measurement module 242 may be employed to measure or record theshape of catheter 210, for example, during or after navigation ofcatheter 210 to a target configuration for a medical procedure. Forexample, after a user has employed navigation module 241 and usedoperator interface 250 to navigate catheter 210 to a targetconfiguration, shape measurement module 242 may be employed to determineand record shape data 249 indicating the shape of at least a distalportion of catheter 210. In the implementation of FIG. 2, a fiber opticshape sensor 264 may extend along the entire length or a distal portionof catheter 210, so that shape measurement module 242 can usemeasurements of the interference of light transmitted on optical fiber,determine the shape of at least a portion of catheter 210, and storeshape data 249 in memory or other storage that control logic 240employs. Such shape sensors using fiber gratings are further describedin U.S. Pat. No. 7,720,322, entitled “Fiber Optic Shape Sensor,” whichis hereby incorporated by reference in its entirety. Otherimplementations could use other systems for sensing the shape of adistal portion of catheter 210. In one implementation, distal steerablesection 216 has the greatest ability to bend, and bends that are toosharp for insertion of a tool may be exclusively or most common at ornear distal steerable section 216 when catheter 210 is in the targetconfiguration.

Shape analysis module 243 can be used to analyze shape data 249,particularly for operations such as insertion or removal of a tool incatheter 210. For example, when a user desires to insert a tool such asa biopsy needle along the deployed shape of catheter 210, shape analysismodule 243 can use shape data 249 and possibly data regarding the toolto identify any bend in catheter 210 that is too sharp for the tool totraverse. More generally, shape analysis module 243 can determinewhether a specific tool can be deployed through or removed from catheter210 while catheter 210 has a target configuration and identify aninsertion or removal configuration of catheter 210 generally or for thatspecific tool. Automatic retract module 244 can then be employed toautomatically (i.e., without user steering) move the distal tip 216 ofcatheter 210 back along the shape indicated by shape data 249 from thetarget configuration to the insertion or removal configuration ofcatheter 210. For example, retract module 244 may automatically retractcatheter 210 just far enough that a specific tool can be inserted to thedistal tip of catheter 210 without undue force or risk. Return module245 may then automatically return catheter 210 to the targetconfiguration by steering the distal tip along the path that shape data249 indicates. Although separate modules are shown in FIG. 2, thefunctions of multiple modules may be combined into a single module,e.g., an automatic retract/return module.

FIG. 4 is a flow diagram of a process 400 for use of a guide tube with atool that may be unable or not permitted to traverse the guide tube inthe target configuration. To provide a definite example, process 400 issometimes described herein with reference to the structure of FIG. 2 andthe illustrated configurations of FIGS. 5A to 5E, but more generally,process 400 is not limited to specific hardware illustrated in FIG. 2 orthe specific configurations of FIGS. 5A to 5E. Process 400 begins with ablock 410 in which the guide tube, e.g., catheter 210, is steered to atarget configuration as shown in FIG. 5A. For example, a user mayactivate a navigation mode implemented with navigation module 241 ofsystem 200 and then control user interface 250 as needed to directcatheter 210 through airways of a patient. Such navigation might includeselecting branches of airways to follow and controlling the pitch andyaw of distal section 216 of catheter 210 to follow selected airways tonodule 122. The guide tube may be empty during performance of navigationblock 410 or may include a probe such as a vision system if the guidetube does not possess a permanent vision system.

In one implementation of process 400, a physician, after navigation tothe target configuration but before inserting a tool in the guide tube,presses a button or otherwise activates an insertion/removal mode of themedical system associated with a guide tube. A block 415 of process 400determines and records shape data indicating the shape of the guide tubein the target configuration. Many techniques for measuring the shape ofthe guide tube can be used. For example, catheter 210 includes a fiberoptic grating sensor 264 that may be used as described in U.S. Pat. App.Pub. No. 2009/0324161, entitled “Fiber Optic Shape Sensor,” which ishereby incorporated by reference in its entirety. With a fiber opticgrating sensor, the shape of all or a distal portion of catheter 210 inthe target configuration of FIG. 5A can be measured. Alternatively, theshape of catheter 210 may be determined by tracking the navigation ormovement of the distal tip of instrument 210 to its target configurationduring process 410. The measured or otherwise determined shape ofcatheter 210 can be recorded, e.g., stored in memory or other storage incontrol system 240 for catheter 210. For example, the determined shapemay be recorded as shape data 249 in any desired format.

The shape data can be analyzed in decision block 420 to identify anylocations in or sections of the target configuration through whichinsertion of a tool is contraindicated. For example, shape analysismodule 243 may identify the locations of any bends in the targetconfiguration of the guide tube that are too sharp for a desired tool totraverse without application of an insertion force deemed to be toolarge. A sharp bend, for example, may be a section of catheter 210 thatextends for more than a specific distance or angle and has a radius ofcurvature that is less than the minimum permitted bend radius. Forexample, shape analysis module 243 may determine a radius of curvatureat each of a series of points associated with the shape data and compareeach determined radius of curvature to a minimum permitted radius ofcurvature for the specific tool. The minimum permitted bend radius maybe selected according to the tool being inserted and may depend on, forexample, the coefficient of friction between the tool and guide tube,the stiffness and length of a critical section of the tool, thestiffness of the guide tube, the stiffness tissue supporting the guidetube, and other factors. Alternatively, an “empirical table” may bedeveloped that indicates whether a section of guide tube is problematicand may be indexed by factors such as flexibility of the tool or thesmallest radius of curvature the tool can accommodate without damage,the radius of curvature of a section of the guide tube, the stiffness ofthe guide tube, and the stiffness of tissue surrounding the section ofthe guide tube. More generally, shape analysis module 243 could use anydesired criterion to evaluate each section of the shape data anddetermine or identify problem sections. In general, a section is aproblem if pushing or pulling the tool through the section requires anunacceptable level of force, and an unacceptable level of insertionforce may be selected based on, for example, risk to a patient, risk ofdamage to the guide tube or tool, or convenience of use of the tool.FIGS. 5A to 5E illustrate a situation in which only a single section,bend 116, is a problem for insertion of a tool through the guide tube.More generally, zero, one, or multiple problem sections may be found.Shape analysis module 243 can determine an insertion or removalconfiguration of the guide tube as being the longest proximal portion ofthe target configuration that does not include any problem sections.

If a decision block 420 determines that the entire target configurationis acceptable for insertion of the tool, a block 425 can be performedduring which the tool is inserted to the distal tip of the guide tubewhile the guide tube remains in the target configuration as shown inFIG. 5D and the tool may be used as described below with reference toFIG. 5E.

If decision block 420 determines that the target configuration of theguide tube is unacceptable for insertion of the tool, e.g., the targetconfiguration includes bends that are too sharp for insertion of thetool, a physician or other user may be informed and may press a buttonor otherwise select to retract the guide tube to the identifiedinsertion configuration. In FIG. 4, a block 430 retracts the distal tipof the guide tube back to a location associated with an acceptableconfiguration, e.g., a location just before the most proximal problemsection of the guide tube in the target configuration or the mostproximal bend that is too sharp for the tool as shown in FIG. 5B. Block430 thus moves guide tube from the target configuration of FIG. 5A to aninsertion or removal configuration as shown in FIG. 5B. In general, theguide tube is only partially retracted, i.e., not fully removed, forexample, because the sharpest bends in the guide tube may be expected tobe close to the distal end of the target configuration. Retraction ofthe guide tube in block 430 can be performed automatically, i.e.,without the need of a user to steer the guide tube. For example, insystem 200 of FIG. 2, a user or control logic 240 on its own initiativemay engage retract module 244, which automatically generates actuationsignals for actuators 222 and 232 from shape data 249, without using orneeding control signals from operator interface 240.

The user can then manually insert the tool into the guide tube. In block435, the tool is inserted to the distal tip of the guide tube while theguide tube remains in the insertion configuration such as shown in FIG.5C. More generally, the tip of biopsy needle 130 may be inserted pastdistal tip 114 or may be short of distal tip 114. Whether a needle isbest inserted to the distal tip of the guide tube, past the distal tipof the guide tube, or short of the distal tip of the guide may depend onfactors such as the stiffness or minimum radius of curvature of thecritical section of the tool and the amount of actuation force that thesteerable section of the guide tube can apply to the critical section ofthe tool. For example, when a tool such as a biopsy needle is softenough that it is bendable by the actuated pitch and yaw of the guidetube, the needle can be inserted to the tip of the catheter, and thecatheter-needle union can just proceed to the target configuration alongthe recorded path either automatically or manually. If the needle isvery stiff, the system can recommend to the user how much the needleneeds to be inserted past (or short of) the distal tip of the catheterto maintain a reasonable catheter-needle stiffness so that thecatheter-needle union can still proceed forward with the recorded path.If the catheter-needle union is too stiff to follow the previouslyrecorded path, the user may still drive the catheter manually. As notedabove, retracting to an insertion configuration allows the tool to beinserted, and at that point, an approach for returning to the targetconfiguration can be chosen.

Performance of block 440, in many situations, can automatically returnthe guide tube with the tool inserted back to the target configurationindicated by the recorded shape data as illustrated in FIG. 5D. Catheter210 can take tool 130 through the problem section or tight bend 116since actuation of steerable distal section 216 may be generally betterable to bend the stiffer section 132 of tool 130 when compared to theforce from the walls of catheter 210 resulting from insertion forceapplied to the proximal end of tool 130. Once the guide tube with thetool reaches the target configuration, block 445 can be performed to usethe tool at the target site. For example, a tool such as a biopsy needlecan be extended beyond the distal tip of the guide tube to interact with(e.g., sample) tissue as shown in FIG. 5E.

Sharp bends or problem sections in a guide tube can also be an issuewhen removing a tool having at least a portion that is less flexiblethan the guide tube. FIG. 6 is a flow diagram of a process 600 forremoval of a tool from a guide tube that is deployed to a targetconfiguration including a bend that is too sharp for the tool totraverse without bending to a radius of curvature smaller than theminimum radius of curvature permitted for the tool. Process 600 beginswith performance of a block 610 that backs the guide tube and tool backto a location just before the most proximal problem section, e.g., alocation associated with the most proximal bend that is too sharp. Onceat that location, performance of block 620 may remove and replace thetool while the distal tip of the guide tube remains in theinsertion/removal configuration. Assuming that the replacement tool hasa minimum permitted radius of curvature that is the same as or smallerthan the radius of curvature of the removed tool, performance of block620 may leave the guide tube in the same position. For example, a biopsyneedle that has taken a tissue sample can be replaced with a new biopsyneedle of the same type, which may be used to take a second tissuesample at the target site. Step 630 can then use the recorded shape datato automatically navigate the guide tube and the inserted replacementtool back to the target configuration of the guide tube. Performance ofblock 640 can then use the replacement tool at the target site.

The automatic retract and return as disclosed above may have advantagesover similar manual procedures. In particular, a physician deploying thebiopsy needle through a catheter could manually retract the catheter tosome location at which the biopsy needle can be inserted to the end ofthe catheter. In general, the manual retraction will take longer than anautomated process and generally will retract the guide tube more than isstrictly necessary. The physician may then also need to manuallynavigate the catheter with the biopsy needle back to the target locationand configuration. The manual back and forth procedure can be very timeconsuming and creates opportunities for errors because the physicianoften needs to do multiple biopsies for the same site, which requiresthe physician to navigate the catheter multiple times through the sameairway or airways. The automatic retract and return processes may takeless time than physician controlled movements. Further, these proceduresif controlled by the physician may require a vision system for thephysician and therefore would be difficult or impossible to perform witha catheter lacking a permanent vision system. Catheters with permanentvision systems may be expected to either be larger or have a smallermain lumen in order to allow space for a vision system, so that theautomatic retraction and return may allow use of smaller catheters thatfit within smaller airways. Further, even if the catheter has a visionsystem, if a nodule to be biopsied is located in the area in which thecamera or other vision system is ineffective such as in a mucus airwayor if the nodule is located in a small lumen into which the catheterdoes not fit, the physician controlled back-and-forth motion may notguarantee that the catheter and biopsy needle returns to the targetedlocation and configuration.

Some implementations described above may efficiently provide a robust,reliable, repeatable, precision biopsy process that requires onlypermitted amounts of insertion force or bending at the tip of the biopsyneedle even when a catheter or other guide tube for the biopsy needleincludes sharp bends. Automated navigation for retraction and returnduring a biopsy procedure can be based on recorded shape data and maysave a tremendous amount of time, particularly when multiple samplesneed to be taken from the same nodule. The work force required in abiopsy procedure may also be reduced when compared to a biopsy task thatmay take more than one physician. For example, in conventionalprocedures, one physician may be charged with navigating thebronchoscope while the other controls the deployment of the needle. Withthe systems and procedures described herein, a single physician may besufficient because the amount of force required to insert a biopsyneedle may be reduced. The automation of repeated backing and returnalong the same airways may also be able to reduce human errors createdduring such biopsies.

Some embodiments of the above invention can be implemented in acomputer-readable media, e.g., a non-transient media, such as an opticalor magnetic disk, a memory card, or other solid state storage containinginstructions that a computing device can execute to perform specificprocesses that are described herein. Such media may further be or becontained in a server or other device connected to a network such as theInternet that provides for the downloading of data and executableinstructions.

Although particular implementations have been disclosed, theseimplementations are only examples and should not be taken aslimitations. Various adaptations and combinations of features of theimplementations disclosed are within the scope of the following claims.

What is claimed is:
 1. A system comprising: a flexible guide tube; anactuator coupled to the flexible guide tube and configured to move atleast a portion of the flexible guide tube; a processor; and memorystoring computer-executable instructions that, when executed by theprocessor, cause the system to: identify at least one factor associatedwith insertion or removal of a tool configured to be inserted through orremoved from the flexible guide tube; identify, in a first configurationof the flexible guide tube and based on the at least one factor, one ormore sections of the flexible guide tube having one or more bends thatthe tool cannot traverse; and command the actuator to automatically movethe flexible guide tube to a second configuration without manualsteering by a user, wherein the second configuration does not includethe one or more bends that the tool cannot traverse.
 2. The system ofclaim 1, wherein identifying one or more sections of the flexible guidetube having one or more bends that the tool cannot traverse comprisesdetermining whether a section has a radius of curvature smaller than athreshold radius of curvature.
 3. The system of claim 1, wherein theflexible guide tube comprises a catheter and the tool comprises a biopsyneedle.
 4. The system of claim 1, wherein the memory further storesinstructions that, when executed by the processor, cause the system toautomatically move the flexible guide tube from the second configurationto the first configuration.
 5. The system of claim 1, wherein theflexible guide tube comprises a shape sensor.
 6. The system of claim 5,wherein the shape sensor is a fiber optic shape sensor.
 7. The system ofclaim 1, further comprising the tool.
 8. A process comprising:identifying one or more problem sections of a first configuration of aflexible guide tube, each of the one or more problem sectionscorresponding to a portion of the flexible guide tube that a toolconfigured to be received by the flexible guide tube would havedifficulty traversing while the flexible guide tube is in the firstconfiguration; automatically moving, via actuation signals sent to anactuator coupled to the flexible guide tube, the flexible guide tubewithout manual steering from the first configuration to a secondconfiguration in which a distal tip of the flexible guide tube is at alocation proximal to a most proximal of the one or more problemsections; and receiving the tool into the flexible guide tube while theflexible guide tube is in the second configuration.
 9. The process ofclaim 8, further comprising moving, from the second configuration to thefirst configuration, the flexible guide tube while the tool is disposedwithin a lumen of the flexible guide tube.
 10. The process of claim 8,wherein identifying one or more problem sections comprises determiningthat a radius of curvature of a section of the flexible guide tube issmaller than a minimum radius of curvature permitted for a portion ofthe tool.
 11. The process of claim 8, wherein identifying one or moreproblem sections comprises determining a shape of the flexible guidetube in the first configuration.
 12. The process of claim 11, whereindetermining the shape of the flexible guide tube in the firstconfiguration comprises measuring the shape of the flexible guide tubein the first configuration using at least one of a fiber optic shapesensor and a tracked movement of the distal tip of the flexible guidetube.
 13. The process of claim 8, wherein the first configurationcomprises a configuration in which the flexible guide tube is disposedwithin a natural lumen, and a distal end of the flexible guide tube islocated at a biopsy site.
 14. A process comprising: identifying a factorassociated with insertion or removal of a tool configured to be receivedby a flexible guide tube; based on the factor, identifying one or moreproblem sections of a first configuration of the flexible guide tube,each of the one or more problem sections corresponding to a portion ofthe flexible guide tube that the tool would have difficulty traversingwhile the flexible guide tube is in the first configuration; informing auser that the first configuration is unsuitable for insertion or removalof the tool; identifying a second configuration of the flexible guidetube that is suitable for insertion or removal of the tool; andautomatically moving, via actuation signals sent to an actuator coupledto the flexible guide tube, the flexible guide tube from the firstconfiguration to the second configuration without manual steering. 15.The process of claim 14, wherein identifying one or more problemsections comprises determining that a radius of curvature of a sectionof the flexible guide tube is smaller than a minimum radius of curvaturepermitted for a portion of the tool.
 16. The process of claim 14,wherein a shape of a first portion of the flexible guide tube in thesecond configuration is substantially the same as a shape of a secondportion of the flexible guide tube in the first configuration.
 17. Theprocess of claim 14, wherein identifying one or more problem sectionscomprises determining a shape of the flexible guide tube in the firstconfiguration.
 18. The process of claim 17, wherein determining theshape of the flexible guide tube in the first configuration comprisesmeasuring the shape of the flexible guide tube in the firstconfiguration using at least one of a fiber optic shape sensor and atracked movement of a distal tip of the flexible guide tube.
 19. Theprocess of claim 14, further comprising: automatically returning theflexible guide tube to the first configuration after the tool has beeninserted into or removed from the flexible guide tube.
 20. The processof claim 19, wherein the returning comprises bending a stiff distalsection of the tool by actuating a steerable distal section of theflexible guide tube.